1. Field of the Invention
The present invention relates to a method for treating waste, such as domestic garbage, industrial waste and the like, in which the waste is suspended in a liquid and the constituents in the resultant waste pulp are separated into mutually different fractions in dependence on their density and/or magnetic properties or like features.
2. History of the Related Art
Many methods of separating and sorting the constituents of waste, such as domestic waste or garbage are known to the art. These methods include screening, magnetic separation and disintegration of the waste constituents by crushing, hammering and shredding. The waste is treated either in a dry or a wet state, either by drying the waste prior to treating the same, or by applying liquid to the waste such as to soak its various constituents and to facilitate transportation of the waste between different treatment stations.
For instance, for the purpose of separating plastics from paper, it is known to separate the constituents of the composite waste material by soaking said material in a first stage and then separating the plastic ingredient from the waste suspension in a second stage. This method, however, cannot be suitably applied as an incorporate stage in a continuous process for treating such wastes as domestic garbage, and is only suitable when treating a particular composite waste material.
Other methods for treating specific types of waste, such as waste paper for recycling, etc., are also known to the art, in which the waste is soaked and treated in different ways in order to separate contaminants from the useful part of the waste.
It can be ascertained that even though there are many processes by means of which the constituents of waste material can be sorted and separated from one another, the end product is often one which can only be deposited in dumps for degradation or decomposition over long periods of time, or incinerated at low incineration efficiency. Even though the end product might contain a large proportion of organic material, this material exists in a form in which decomposition takes a very long time, or in a form which makes effective incineration combustion difficult to achieve or which even requires input of additional of energy.